Post fracture tensile test

Drop weight, standard and precracked Charpy impact, tensile test, and compact tension fracture toughness specimens are provided for unirradiated tests. Drop weight tests will be conducted in accordance with ASTM E-208. Charpy impact tests will be conducted in accordance with AGTM E-23. Tensile tests are conducted in accordance with ASTM E-8 and E-21. Correlation of drop weight and Charpy impact tests to establish will be made in accordance with NB2300 of the ASME Code, Section III. Charpy impact and tensile test specimens are provided for post-irradiation tests. 

The problem of secondary flexure in axial tensile tests is considered in view of the tension-softening process. The procedures aimed at elimination of that parasite effect were studied by Akita et al. (2001) and Novak et al. (2006) who have shown possibilities of nonlinear fracture mechanics simulation in analysis of the experimental data, including post-peak descending branch of the load-displacement curves, taking into consideration material imperfections and heterogeneities. 

Test Procedures - Generally, a displacement-control or strain-control test mode is used to avoid run-away tests that sometimes occur in force-control. A test mode rate is chosen so as to produce test specimen failure in 5-50 s. Failure within 1 minute or less should be sufficient to minimize slow-crack growth (SCG) effects in the tensile test. If slow crack growth is observed (e.g. under slow test mode rates), subsequent tests can be accelerated to reduce or eliminate slow crack growth. Extensometers and/or strain gages are used to determine gage length extension and/or local strain. The test specimen is tested in flexure to fracture. The test specimen is retained for failure analysis and post-test dimensional measurement. 

Post-test metallographic examination of longitudinal sections of composite weld tensile samples provided data on the location of the fracture and the presence of secondary intergranular cracking. Base metal fracture locations were experienced with K-58 GTA welds at room temperature (RT), K-58 GTA/CW/PR (see Table II for notation) and K-58 GTA/CW/FR welds at all temperatures, Pyromet 538 GTA welds at all temperatures, Pyromet 538 SMA welds at RT, and A-286 GTA welds at RT. Weld FZ fractures were experienced with all 310S SMA welds, K-58 GTA welds below room temperature, K-58... 

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